The development of computer systems resulted in a widespread use of computer technology in the music industry, for example in recording of the sound, in mixing, and in computer aided composing and generating of improvised music.
The implementation of computerised music improvisation offers great opportunities, because the spreading of musical compositions in a digital way—even in the age of efficient compressing methods and high capacity data sources—is restricted by the substantial size of digitised musical compositions. In applications where it is necessary to generate background, incidental or other improvised music, i.e. where the object is not the playing of a particular composition, but an algorithmised improvised music is to be generated in a predetermined style, for example classical, pop, dance music, techno, jazz, applied music etc. on the basis of pre-stored audio data, the storing of the audio data could require a much smaller storage capacity than in the case of storing complete music pieces even in a compressed form.
A method and an apparatus for automatic generation of music of improvised character are described for example in U.S. Pat. No. 5,281,754. This known processor controlled apparatus is designed for improvised playing of pre-stored musical material in the form of a music piece. The apparatus has a memory comprising musical phrases consisting of melody and musical instrument data, from which by means of a random number generator a random sequence of phrases is selected, an accompaniment is generated for the melody of the phrases, random musical instruments are selected for the melody and the accompaniment, and then the musical phrases so generated are supplied to a synthesiser for generating audio signals. The disadvantage of the apparatus is that it generates the music in MIDI format and hence a MIDI compatible synthesiser is required to play the music. The MIDI compatible synthesiser makes the apparatus much mote expensive and furthermore the quality of music generated heavily depends on the quality of the synthesiser. At present, realistic music cannot be generated by means of this known apparatus. A further disadvantage of the apparatus is that it does not allow an arbitrary number and combination of solo instruments to sound at the same time, and so the improvisation is narrowed down to a relatively small range.
An apparatus for an electronic organ serving for generating an improvised accompaniment is described in U.S. Pat. No. 4,616,547. The apparatus stores rhythm and pitch patters and combination rules related thereto in a coded form. The rhythm and pitch patterns are read at random by the apparatus and according to the user's adjustments it improvises an accompaniment to the melody played by the user. This known apparatus is not suitable for generating music per se, because its outputs are linked to the inputs of the electronic organ's sound generating circuits. Therefore, this apparatus can only be used when it is fitted into an electronic organ.
In WO 97/21210 A a method and an apparatus is disclosed for interactively creating new arrangements for musical compositions. A plurality of musical sequences and a template specifying a plurality of fixed sequence positions for arrangements are stored in a database. A user interactively selects from the plurality of fixed musical sequences and interactively allocates the selected sequences among various fixed sequence positions defined by the template, thereby creating a new arrangement. However, this known solution is not suitable for improvising music by a computer program, as the generated music is a result of a particular user arrangement and not of a randomised improvisation according to predetermined improvisation rules.